Theorem 2.1 [1]}
Let \(f:\mathbb {R}^n\rightarrow \mathbb {R}\)  is an \(L\) -smooth convex function for some \(L>0\) . If \(t_k=\tfrac{1}{\ell _{\max }}\)  for all \(k\) , then, for each \(k > 0\) ,
\(\mathbb {E}\left( f(x^{k}) \right)-f^\star \le \left(\tfrac{2n\ell _{\max }}{k}\right) R_0^2,\) 
